The notion of beauty can mean different things to different artists. For the stop-motion animators the Brothers Quay, it often means dimly lit black and white images of dolls, screws, cogs, any manner of inanimate object brought to life. For their latest effort, the Quays were invited to film at the Mutter Museum in Philadelphia. It houses a collection of 19th-century medical curiosities.

NPR's Christopher Joyce watched the brothers making the film, which opens tomorrow in Philadelphia.

CHRISTOPHER JOYCE: Timothy and Stephen Quay hover over a table in the museum room they've turned into a darkened studio. The Quays are twins, lean, fashionable in a comfortable way, with long, graying hair. They're in their 60s, but don't look it. It's hard to tell them apart and they like it that way.

Behind them, the soundtrack from David Lynch's "Twin Peaks" plays ominously. They place museum specimens on the table under shimmering lights - a fetus in a jar, a terrifying sort of metal plunger for removing kidney stones. As yet, they have no script, no storyline.

STEPHEN QUAY: What we most like are the accidents, and the accidents bend the direction of the film.

TIMOTHY QUAY: Because the whole thing about this museum is discovering that one little kernel or that one strange event.

JOYCE: When the Quays describe their work, they speak as one, undifferentiated. They rotate and film the objects from different angles, conferring quietly, building mood. The Quays say this museum is both heartrending and beautiful.

And watching a Quay film is kind of like being in a museum, looking at a diorama through a peephole. You might call it a dreamscape, but they say, no, it's crepuscular. It's the slippery moment just after you wake up, between sleep and wakefulness.

QUAY: For us, it's always been the in-between world where it's an ambiguous state and it shimmers in a kind of half state, like maybe it's a little bit where reality and fiction tremble with a nice...

QUAY: Favorable.

QUAY: ...favorable wind.

JOYCE: It's worth noting that the Quays usually keep lots of Belgian beer nearby when filming or doing interviews.

(SOUNDBITE OF MUSIC)

JOYCE: Before the Quays begin filming, they usually decide on the music and let it guide them. Tim Nelson composed the music for the Mutter film.

TIM NELSON: They're looking more for the moments where there might be something that sticks out, that little sound there that might inspire a reflection off glass or when the camera angle would change or something like that. They find the rhythms within the music.

JOYCE: And the music helps give meaning to the objects. The Quays grew up near Philadelphia and studied art there before moving to England. They were invited back by Robert Hicks, who came to the Mutter Museum two years ago with a mission to open its collection to artists. Many came, but it was these painterly animators he really wanted.

ROBERT HICKS: The Quay brothers are so good at revealing the hidden, at creating stories about the inner lives of overlooked or unusual things. They animate straight pins used in sewing. They animate puppets, screws, dust. They're particularly virtuosos manipulating dust.

JOYCE: In fact, the brothers had visited the museum in their teens, so they knew about its bizarre offerings.

ANNA DHODY: My name is Anna Dhody and I'm the curator.

JOYCE: Dhody is also a forensic scientist. She solves criminal mysteries based on bodies or bones. Mutter's main exhibition hall has plenty of both, like the 139 human skulls on the wall. Each has an identifying tag.

DHODY: Giza Hermenyi, reformist herdsman, at age 70 attempted suicide by cutting his throat. Wound not fatal because of ossified larynx. Lived until 80 without melancholy.

JOYCE: In another cabinet, a skeleton stands erect and looks very melancholy. There's something very wrong with the bones.

DHODY: This is Harry Eastlack, and Harry has something called fibrodysplasia ossificans progressiva.

JOYCE: As Eastlack aged, any bump or injury caused more bone to grow inside him in places it shouldn't. In the end, Eastlack could only move his lips. He died at 39 and asked that his skeleton stay at Mutter. And his story is how the Quays start their story.

QUAY: Harry Eastlack is the one that we're sort of creating a kind of through-line, but you know, then there's these curves, other events sweep in and intersect.

JOYCE: While the brothers film, Dhody and director Robert Hicks are off gathering objects that have caught their fancy.

HICKS: We're looking at what looks like a bust of a classical head and it's meant for practicing eye surgery.

JOYCE: It's called an eye phantom, a 19th-century metal sculpture with empty eye sockets. Students would place eyeballs in the sockets. It's Anna Dhody's job to do that for the Quays.

DHODY: Prepping the eyeballs to get them into the eye phantom and then I don't know what they're going to be doing.

JOYCE: But these are real eyeballs?

DHODY: Cow, sheep and pig.

JOYCE: Prepping entails carving down the over-large eyeballs so they'll fit into the human-sized sockets. The eyes finally stay put and she presents the thing to the Quays. They stare for a while, then politely say, hmm, doesn't quite work. But they are taken with the 139 skulls. There are stories there.

QUAY: Every one of them had a - made a journey, and it's true. It's like what would be the five lines that would describe each one of us personally?

QUAY: The trajectory of life and how you ended.

QUAY: Yeah.

QUAY: How you ended in this museum, as well.

JOYCE: The filming takes several days. Only after will the Quays shape the whole film.

QUAY: We never walk through the front door. We insist on coming through the side door or the back door. It's a bit like a plant growing in a sense that you just keep it watered. It might grow three limbs on one side and only one on the other, but it will be striking or it will be special.

QUAY: Or a perversion.

JOYCE: The film is called "Through the Weeping Glass: On the Consolations of Life Everlasting." Unusually for a Quay film, there is narration by the Shakespearean actor Sir Derek Jacobi. The first line, no child ever imagines the unimaginable, that he will end up as a skeleton.

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